There are just four simple rules of the Billings Ovulation Method™ which are applicable in all circumstances and at all stages of reproductive life.

The Early Day Rules apply to the days before ovulation.

1.    There should be abstinence from intercourse and all intimate genital contact during the days of heavy menstrual bleeding.  This is because in a short cycle fertility may begin before the bleeding has finished and the presence of the mucus which indicates fertility could be masked by the bleeding.

2.    Once the Basic Infertile Pattern has been recognised – days of dryness or unchanging discharge – intercourse is available on alternate evenings only.  This is firstly because waiting until evening will allow the woman to be sure that the mucus pattern indicating possible fertility has not begun – she needs to be upright and moving about for a few hours for the mucus to flow down to where she can become aware of it at the vulva.  Secondly, the day after intercourse she may feel damp and see a discharge of seminal fluid which could mask the beginning of the mucus pattern – intercourse is not recommended on consecutive evenings to allow for this occurrence.  The seminal fluid detected on the day after intercourse will not contain any live sperm.  Thus, even if the mucus starts in the hours following intercourse there will be no sperm capable of reaching and fertilizing the ovum.

3.    Once there is any change from the Basic Infertile Pattern, whether it be bleeding or mucus – a change in sensation or in the appearance of the discharge – the couple should wait without intercourse to see what happens.  If the Peak is observed the Peak Rule can be applied.  If the Basic Infertile Pattern returns the couple should wait for a further 3 days and then resume using Rule 2 from the fourth evening.  Waiting without intercourse allows the woman to observe the development of the mucus pattern without interference from seminal fluid.  Waiting for 3 days after the return of the Basic Infertile Pattern ensures that the hormones have settled back to a basic low level and the cervix is tightly closed.

The Peak Rule is applied once the Peak has been recognised. 
(The Peak is the last day of the slippery sensation of a changing developing pattern of variable length.
It is recognised in retrospect when there has been a distinct change to no longer slippery.) 

From the fourth morning past the Peak, intercourse is available on any day, at any time, for the remainder of the cycle.  Waiting until the 4th day past the Peak allows time for ovulation to take place and for the life of the egg.  For the remainder of the cycle the couple is infertile because the egg is dead and there won’t be another ovulation until after the next menstruation.

Menstruation follows the Peak 11-16 days later in a normal fertile cycle.

To avoid pregnancy the couple should apply the Early Day Rules and the Peak Rule.

To achieve a pregnancy the couple should apply the Early Day Rules in order to be able to correctly identify when the woman becomes potentially fertile.  They should then abstain until she notices the slippery sensation.  Intercourse over the days when the vulva feels slippery, at the time of the swollen vulva, and on the first one or two days past the Peak will afford the best chance of conceiving.

Accurate interpretation of the individual patterns of fertility and infertility and correct application of the guidelines is best learnt with the help of your Billings Ovulation Method™ tutor.